Connecting means and method for reinforcing rods



May 31, 1966 G. H. HOWLETT ET AL 3,253,332

CONNECTING MEANS AND METHOD FOR REINFORCING RODS 2 Sheets-Sheet 1 FiledMay 14, 1963 35 INVENTOR.

Georc e H. How/eff- 4 Jams-:5 W Haw/679' 4, i5 Q74 2W H- HOWLETT ET ALCONNECTING MEANS AND METHOD FOR REINFORCING RODS Filed May 1963 FIG. 3

2 Sheets-s 2 INVENTOR. George w/eh mes W How/eff B hi/ W 3,253,332CONNEQTING MEANS AND METHOD FOR REINFORCING RODS George H. Hewlett,Oakland, and James W. Hewlett, Richmond Annex, Calif., assignors toHowlett Machine Works, a corporation of California Filed May 14, 15 63,Scr. No. 280,357 1 Claim. (Cl. 29-506) The present invention relates toreinforced concrete construction which utilizes lengths of steel rods orbars positioned within the concrete pour, and more particularly todevices and methods for splicing such rods or bars in end to endconnection. Where the concrete structure has a length greater than thelength of the bars, continuity of the reinforcement is dependent uponsplicing of the bars. Heretofore, it has been the practice to weldreinforcing rod ends together.

An object of the present invention is to provide a connecting means andmethod for reinforcing steel rods which will avoid the necessity ofwelding and instead provide for the gripping and coupling of adjacentconfronting rod ends to be joined in an all mechanical coupler whichwill afford maximum strength in both tension and compression permittingengineers to design structures using 100% of the physical properties ofall of the various grades of reinforcing steel without making allowancesfor the uncertainty of welding; and which permits the splicing of highstrength alloy steels which are difficult to weld and in general topermit the use of all available steels without regard to weldingproperties.

Another object of the present invention is to provide a connecting meansand method for reinforcing steel rods which permits a more rapid andeasier installation enabling the contractor to expedite the work byreducing installation time to a fraction of the time required for weldedconnections and their repair when not satisfactory, and to accomplishthis more rapid installation with a minimum of extra equipment andWithout expensive handling equipment and without the use of skilledmechanics, thereby permitting form work to proceed more rapidly and thusfurther cooperate with the utilization of full properties of the steelin effecting an overall reduction in cost of construction.

A further object of the present invention is to provide a connectingmeans and method of the character described and which will produce apositive connection of reinforcing steel bars in a manner which permitsready inspection enabling the project inspector a positive means ofexamining a joint for acceptability without resorting to X-rays or othersimilar means of examination, and which connection when made inaccordance with the present invention is permanent and not affected byheavy or continuous vibration.

The invention possesses other objects and features of advantage, some ofwhich of the foregoing will be set forth in the following description ofthe preferred form of the invention which is illustrated in the drawingsaccompanying and forming part of this specification. It is to beunderstood, however, that variations in the showing made by the saiddrawings and description may be adopted within the scope of theinvention as set forth in the claims.

Referring to said drawings (two sheets):

FIGURE 1 is a perspective view of a concrete structure and reinforcingrods prepared and assembled with the coupling device and method of thepresent invention, portions of the view being exploded for betterillustration of the device and method.

FIGURE 2 is a side elevation of a pair of joined reinforcing rods andcoupling device of the present invention, with the latter broken awayand shown partly in crosssection.

United States Patent 3,253,332 Patented May 31, 1966 'ice FIGURE 3 is anenlarged side elevation partly in section of a part of the couplingdevice showing assembly.

FIGURE 4 is a longitudinal cross-sectional view of the apparatus usedfor setting the wedge sleeves in an intermediate step of the method ofthe present invention.

The connecting means of the present invention is particularly adaptedfor splicing reinforcing steel rods or bars 11, 12, 13, 14, 15, 16 and17 as illustrated in FIGURES 1 and 2 of the drawings, and consistsbriefly of a pair of longitudinally split sleeves 21 and 22 formed witha pair of external spiral cam lands 23 and 24 of reverse pitch and withserrated interior surfaces 26 and 27 dimensioned for gripping theperipheries of each pair of rods to be joined, such as rods 16 and 17 inFIGURE 2; a tubular housing 28 formed with a pair of internal spiral camlands 31 and 32 of reverse pitch extending inwardly from the oppositeends 33 and 34 of the housing 28 and formed to receive in matingthreaded fit the cam lands 23 and 24 on sleeves 21 and 22; and means 36for rotating housing 28 relative to sleeves 21 and 22 to compress thesleeves into tight gripping engagement with rods 16 and 17 and todisplace the rods axially toward each other in end to end compressionapproaching the yield point of the rods. Preferably, the sleeves arepositioned adjacent the confronting aligned ends 37 and 38 of thereinforcing rods 16 and 17 to be joined so that rotation of the housing28, as above noted, will cause, by reason of the reverse pitch of thepairs of mating cam lands 23, 24 and 31, 32 an axial displacement of therods into abutment of confronting rod ends 37 and 38. The serrations onthe interior surfaces 26 and 27 of the two sleeves may be formed bycutting a spiral thread into these surfaces to define fine annular sharpteeth which are adapted for embedding in the periphery of the rods. Inthis connection, it may be observed that the sleeves 21 and 22 as wellas the housing 28 are formed of high strength hardened steel so as topermit their use with all commercial grades of reinforcing steel and theapplication of requisite forces, as described herein. i

As will be observed in FIGURE 2, the cam lands 23, 24 and 31, 32 arefashioned as spiral threads but with one side of the thread (forming thecam land itself) formed long and relatively fiat and at a small angle ofincline with respect to the longitudinal axis of the coupling; and withthe other side of the thread formed as an offset shoulder having alarger angle, nearly perpendicular, to the axis. For purposes ofidentification, the shoulders formed in the housing at the edge of thespiral convolutions forming cam lands 31 and 32 have been givenreference numerals 41 and 42; and the shoulders formed as spiralconvolutions at the longitudinal ends of cam lands 23 and 24 of the twosleeves have been given reference numerals 43 and 44. The fashioning ofthe relatively flat elongated cam lands arranged essentially end to end,as viewed in longitudinal section in FIGURE 2, affords a structurewherein essentially the entire length of the sleeves, andcorrespondingly the engaged length of the housing, acts with wedgingaction on the engaged rods 16 and 17 when the housing is rotated,clockwise as viewed in FIGURES l and 2, relative to the sleeves androds. As will be observed from FIGURE 2, cam lands 24 on the uppersleeve 22 and rod 17 diverge outwardly relative to the longitudinal axisof the device in the direction of rod end 37. At the same time, thespiral pitch of the engaged cam lands 24 and 32 will cause the sleeve tomove inwardly toward the center of the housing upon relative clockwiserotation of the housing. The other set of cam lands 23 and 31 on thesleeve and housing at the lower end of the assembly, as seen in FIGURE2, also diverge in an axial direction toward the center of the housingand the pitch of these engaged lands is such as to cause relativemovement of the lower sleeve 21 toward the center of the housing uponthe rods.

is satisfactory for this purpose.

upon relative clockwise rotation of the housing, as above noted.Accordingly, two important effects occur upon the above describedrotation of housing28. One, the wedge action of the engaged cam landsforce the sleeves tightly against rods 16 and 17 and the greater therotational force applied to the sleeve, the greater the compressiveaction of the sleeves on the rods. The forming of the sleeves withlongitudinal slotted portions 46 and 47 permits the readycircumferential tightening of the sleeves The second important action isthe axial displacement of the rods towards each other so as to place theconfronting rod ends 37 and 38 into compression abutment. It is afeature of the present invention that sulficient torque is applied tothe housing to apply endwise compression loads on the rods to a pointapproaching the yield point of the rods themselves. The two joined rodsthus become in effect one solid rod with a strength in tension andcompression equivalent to the full maximum strength of the individualrods. While the rods are placed in end to end compression as aboveexplained, the housing is placed in corresponding tension and must havea cross-sectional area and strength capable of carrying the load with anadequate factor of safety. Preferably, as above noted, the housing isformed of high strength steel having a tensile strength in excess of 150thousand pounds per square inch, and the housing is designed with acrosssectional area somewhat greater than the rods which the housingjoins. The internal sleeves are preferably of hardened steel so as totake a proper bite into the rods, and we prefer sleeves having ahardness of approximately 60 on the Rockwell C scale (file hardness).

Any suitable means may be used for torquing up the assembly. A torquewrench, as illustrated in FIGURE 1, It consists of a long handle 51 forobtaining leverage and which is formed at one end with a fixed jaw 52having a segmental cylindrical face adapted to engage a portion of theperiphery of the housing 28. A second circular jaw 53 is pivotallysecured as by bolt 54 to swing into a complementary circumferentialengagement of housing 28 opposite jaw 52, the shape and mounting of jaw53 serving to grip the housing tightly upon the application of aclockwise rotary movement to handle 51, as seen in FIGURE 1 and assuggested by arrow 56. A longitudinally extending indicator bar 57 isanchored at one end to handle 51 adjacent the jaw section, as by screws58, and extends longitudinally in overlying relation to the handle intojuxtaposition of its outer end a full circumferential grip of the rods.

tools. For many installations the bevelling of the rod ends is notrequired.

As will be appreciated, conventional reinforcing rods or bars are formedwith a series of longitudinally spaced annular ribs or shoulders 66 andwith one or more longltudinally extending ribs 67 for better gripping ofthe concrete. These ribs are removed at the rod area 68 gripped by thesleeves, see FIGURE 3, so as to afford the sleeves The reinforcing barsto be joined may either be cold-pressed round to remove the deformations66 and 67 or the rod end portions may be turned with a suitable toolsuch as a bolt threader, or the like. Ideally, the ribs 67 and 68 shouldbe just removed but the taking of some additional material, perhaps0.010 inch to 0.030 inch, may be desirable to obtain a cylindricalsurface and correct for minor irregularities in the bars.

The next step in the assembly, as depicted in FIG- URE 3, is to slide onthe sleeves 21 and 22 moving them over the confronting ends of thereinforcing bars to be joined and onto the cleared portion 68. As abovenoted, right and left hand threaded sleeves are selected for the two barends. Preferably, and in accordance with a desired intermediate step ofthe present method, the sleeves are set onto the bar portions 68 bypress fitting the sleeves thereon prior to the mounting of the outerhousing 28. An apparatus for setting the sleeves is illustrated in FIG-URE 4 and consists of a tubular body 71 having an interior spiral camland 72 formed in the same manner as the cam lands in housing 28 so asto receive in mating threaded fit the cam land 23 of sleeve 21.Accordingly, after sleeve 21 has been slid onto the end portion 68 ofrod 16, the sleeve and rod assembly may be threaded into one end 73 ofthe body 71, as illustrated in FIGURE 4.

with a lateral torque scale 59. Rotary displacement of the handle may beeffected by any convenient power means or by block and tackle, or thelike. Provision is made for this purpose for cable attachment to thehandle, see clevises 61 and 62 fastened to the handle 51 adjacent itsouter end 63.

Preferably, the periphery of housing 28 is knurled or otherwise providedwith a series of longitudinally extending teeth 64 which will interfitwith similarly formed teeth on the interior faces of jaws 52 and 53 soas to provide an improved and adequate gripping of the wrench on thehousing. Other conventional types of wrench surfaces such as polygonalflats and the like may be used. The wrench 51 should be designed towithstand and to apply torque to the housing in the order of up to about10,000 foot pounds.

As a feature of the present invention the confronting rod ends 37 and 38may be bevelled, as seen in FIGURES l and 2, so that when the rods arepositioned in face to face fit, as seen in FIGURE 2, they will be fittedtogether in rotationally interlocked relation. Thus, one rod may notrotate relative to the other rod. This construction cooperates with thereverse pitch of the spiral cam lands to provide a positive'locking upof the assembly and holding fast of the parts against heavy andcontinuous vibration. Preparation (bevelling) of the rod ends where thisfeature is to be used may be done in a fabricating shop or in the fieldby the use of appropriate portable cutting As will be observed in FIGURE4, the mated cam lands 23 and 72 diverge in an interior axial directionso that force applied to the internal end 37 of the rod will cause themated cam lands to wedge the sleeve tightly into compression around therod end portion 68. The opposite end portion of body 71 is formed with asmooth axially aligned cylinder 74 which is adapted to receive for axialreciprocation a cylindrical plunger 76 which may be inserted intocylinder 74 from one end 77 of the body. The interior end 78 of plunger76 is formed as an anvil for abutment against rod end 37 for applyingaxial force to the rod. The assembly, as illustrated in FIGURE 4, isthen placed in a power operated press such as a hydraulic press andforce applied axially between end 73 of the body and the opposite end 79of plunger 76, as indicated by force arrows 81 on end 73 and force arrow82 on plunger end 79. Preferably, the force applied to set the wedgesleeve is up to approximately the yield point of the material of thereinforcing bar 16 and accordingly, the hydraulic press should becapable of applying pressure upwards of 75,000 pounds per square inch.The application of such a force within the apparatus, as illustrated inFIGURE 4, fully embeds the interior sleeve teeth 26 into the rodperiphery and evens out all minor inaccuracies in tolerances in the rodand sleeve so that all of the cam land surfaces are brought intoparallel concentric relation.

After the sleeves 21 and 22 have been set upon the confronting rod endsto be joined, as illustrated in FIG- URE 4, the rod ends are insertedinto the opposite ends of the housing 28 and the latter rotated in orderto draw the rod ends internally into the interior of the housing andinto abutment, as illustrated in FIGURE 2. Torque wrench 51 may then beapplied, as illustrated in FIG- URE 1, and block and tackle or othermeans applied to torque up the assembly, as hereinabove described. Theuse of a torque wrench as illustrated is convenient in enabling theproject inspector to visually observe the amount of torque applied tothe coupling to make sure that a positive and foolproof joint isprovided. The inspector may also observe the yielding of the one rodwhich is normally anchored in concrete such as rods 11, 12, 14 and 16 inFIGURE 1. Experience will indicate the approximate yield point of therods.-

The coupler of the present invention may be readily dimensioned for usewith all of the conventional reinforcing bar sizes extending from 188having a diameter of 2.257 inches down to size 5 having a diameter of0.625 inch; and may be used with all of the usual grades of reinforcingsteel such as A.S.T.M. A-15 and A-408, billet steel, intermediate andhard grade, A.S.T.M. A-431, billet steel, 60,000 p.s.i. yield point,A.S.T.M. A-432, high strength billet steel, A.S.T.M. A-16, railsteelregular and special, A.S.T.M. A-160, axle steel, structural,intermediate and hard grade.

The coupling will withstand bending of reinforcing steel to 30; and thecoupling is suitable for all deformations under A.S.T.M. specificationA-305.

We claim:

The method of splicing structural rods which comprises mounting on apair of rods to be joined a pair of tubular longitudinally split sleevesformed with a pair of external circumferentially extending spiral camlands of reverse pitch and with generally cylindrical interior surfacesdimensioned for fitting the peripheries of said rods and with internallyprojecting teeth adapted for embedding into said rods, compressing saidsleeves upon said rods adjacent ends thereof to be joined by holdingeach of said sleeves in a surrounding mating cam land and applying anaxial load to the interior mounted rod substantially equal to its yieldpoint thereby obtaining a corresponding pre-set embedding of said teethin said rods, thereafter engaging said sleeves in a tubular housingformed with a pair of interior spiral cam lands of reverse pitch formedto receive in mating threaded fit said first mentioned cam lands, androtating said housing relative to said sleeves to displace said sleevesinto compressive gripping engagement with said rods and to displace saidrods into end to end compression.

References Cited by the Examiner UNITED STATES PATENTS 960,377 6/1910McLean 285-328 1,435,028 11/1922 Stewart 285-417 1,646,660 10/1927Prince 287--114X 1,712,108 5/1929 Goeller 287-114 1,833,008 11/1931Thorpe 287119 1,901,286 3/1933 Coe 287-60 2,051,499 8/1936 Siegle285-417 2,382,003 8/1945 Cones 287 60 2,453,079 11/1948 Rossmann -128 X2,930,642 3/1960 Howlett 287-114 FOREIGN PATENTS 659,899 2/ 1929 France.

OTHER REFERENCES Stressrods, Rods, Inc., page 8 relied upon.

CARL W. TOMLIN, Primary Examiner.

